The influence of the autonomic nervous system on intestinal absorption and secretion of salt and water will be studied in anesthetized rats by acutely interrupting the nerve supply to intestinal segments. Nerve conduction will be interrupted by excision or by topical application of agents that block nerve conduction. Studies will also be conducted on isolated rabbit intestinal mucosa mounted in a special flux chamber designed to make it possible to depolarize the neural ganglia. The short circuit current, and unidirectional fluxes of Na and Cl will be measured during a control period, and contrasted with the measurements made when the neural plexuses are depolarized.